These test methods are limited to the determination of the velocity of two types of horizontally travelling seismic waves in soil materials. GEOPHYSICAL SYSTEMS. NDE ™» One Platform – Multiple NDE Tests geo- Crosshole/Downhole Seismic» ASTM D/DM/D(DS). Crosshole seismic test procedures are outlined in ASTM test designation D M (). The ASTM procedures provide specific.

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Typically, geophysical borehole logging will be conducted in each drill hole for the purpose of defining lithologic and stratigraphic continuity of the deposits.

Standard Test Methods for Crosshole Seismic Testing

Acquiring crosshole seismic data resolves hidden layer velocity anomalies that cannot be detected with conventional surface methods, allows both final interpretation of other surface geophysical data seismic or electricaland permits both empirical and theoretical correlation with other geotechnical material parameters.

Borehole verticality and direction azimuth measurements should be performed at every depth interval that seismic data are acquired. Also, depending upon the velocity contrast across layer boundaries, direct arrivals through low-velocity layers are generally larger amplitude and thereby recognizable.

The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.

General Crosshole Procedures Introduction The primary purpose of obtaining crosshole data is to obtain the most detailed in situ seismic wave velocity profile for site-specific investigations and material Characterization. Due to the different particle motions along the seismic ray path, it is crucial to use optimal source-receiver systems in order to best record crosshole P- or S-waves Hoar, Also included is an optional method intended for use on projects which do not require measurements of a high degree of precision.

This is accomplished with loading poles or with geophones that can be electronically oriented. Figure 5 shows a portion of the waveforms collected over the depth interval Even small grout takes begin to affect the velocity measured between two closely spaced drill holes. Compare T rfr with T dir and T meas. P-waves are generated with a sparker or small explosive device one that will not damage the PVC casing such that along the assumed straight-ray propagation path the seismic impulse compresses and rarefies the materials radially toward the receiver borehole s.


Crosshole seismic testing has the unique advantage of sampling a limited volume of material at each test depth. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Direct and fairly straightforward computation of the S-wave velocity profile, which is correlated with the liquefaction potential of both the materials and depth intervals of engineering concern for the safety of the structure.

With three-component geophones, there is one vertically oriented geophone and two horizontal geophones.

As the vadose zone and water surface are encountered, P-wave velocities become dependent upon the percent saturation, and the Poisson’s ratio is no longer a valid representation of the formation characteristics. In these soil conditions, computing an average velocity from the two direct velocities i.

Historical Version s – view previous versions of standard. The primary purpose of obtaining crosshole data is to obtain the most detailed in situ seismic wave velocity profile for site-specific investigations and material Characterization.

Direct-wave velocities computed for the far receiver R2 at each depth will always be slightly higher than the near receiver R1 ; hence, the interval velocity will be even higher. Compute total refracted travel time: Alternatively, SH-waves can be asstm and recorded in crosshole testing. Compute abscissa distance Y i: Example Problem Xstm illustrate the effect of a high S-wave velocity layer overlying a low S-wave velocity layer on crosshole waveforms, the following sample problem is presented using data acquired at a site in central Utah.

Matching the formation density with a grout mix is not too difficult, but in open coarse-grained soils, problems arise during grout completion with losses into the formation. The pages found under Surface Methods and Borehole Methods are substantially ba sed on a report produced by the United States Department of Transportation: Because only body waves are generated in the source borehole during crosshole tests, surface waves ground roll are not generated and do not interfere with the recorded body-wave seismic signals.


ASTM D / DM – 00 Standard Test Methods for Crosshole Seismic Testing

Link to Active This link will always route to the current Active version of the standard. Link c4428 Active This link will always route to the current Active version of the standard. Data reduction and interpretation is limited to the identification of various seismic wave types, apparent velocity relation to true velocity, example computations, effective borehole spacing, use of Snell’s law of refraction, assumptions, and computer programs.

Some deposits have linearly increasing velocity with depth, primarily due to vertical pressures, where the apparent asmt for each depth can be computed with. Jump to main content. Due to the effect refracted waves have on crosshole data sets, ASTM procedures require a three-borehole array because velocity corrections can be made for refracted arrivals.

Standard – Standard Test Methods for Crosshole Seismic Testing ASTM D/DM –

Increasing velocity with depth implies the seismic ray path is nearly circular between source and receiver, thereby sensing deeper higher velocity material as the source-receiver separation increases. Another critical element of crosshole testing, which is often ignored, is the requirement for borehole directional surveys. In this system, the pound lbf represents ast unit of force weightwhile the unit for mass is slugs.

This sample problem, or example data set, illustrates three distinct advantages that crosshole testing has over conventional surface geophysical testing atsm these types of investigations: The d44288 trigger signal from zero-time geophones or accelerometers mounted on the downhole impact hammer allows accurate timing for the first arrival at each drill hole.

The comparative technique for defining the refractor velocities outlined above assumes that the velocities are constant within each layer; however, occasionally this is an oversimplification. This permits timing direct arrivals directly off the waveform.

Assuming that the boreholes are vertical and plumb leads to computational inaccuracies and ultimately to data that cannot be quality assured.

Reporting of test results in units other than SI shall not be regarded as nonconformance with this test adtm.